We have developed a flexible impact force sensor using a piezoelectric film. The sensor is distribution type in which sensor elements with 30mm square are arranged in a matrix with regular intervals. Each sensor element is a rigid plate structure. Flexibility of the sensor is achieved by the flexible leather connections between adjacent sensor elements. There is no electrical wiring in the sensor. The output signal of the sensor element is obtained from the conductive cloth via upper and lower metal plate of the elements. The authors are challenging to make smaller the size of sensor element, make thinner of the sensor thickness and to remove perfectly the electrostatic effects. In order to realize these, we are in the current situation of repeated prototype testing. In this study, we have conducted three experiments using the prototype sensors, that is, boxing punching test of sandbag, the seating impact test of an office chair, and bamboo sword beating test of kendo forearm.
A navigation and communication system utilizing roadside beacons is under development. The functions and infrastructure of the Road/Automobile Communication System are outlined, the in-vehicle equipment is described and the results of field tests conducted in the Tokyo/Yokohama area are reported. The system provides the driver with such information as present location and traffic conditions, plots optimum and alternative routes to destination, and enables limited two-way communication to be made. Field testing indicates that the navigation and route-search functions are of great benefit to drivers in an unfamiliar area. However, route-search calculation time must be reduced, especially for route revision in response to incoming data.< >
Effect of powder particle size, extrusion temperature and mean strain rate on anisotropy of MnAlC alloy was investigated. The anisotropy proceeding mechanism of MnAlC alloy was considered by anisotropy investigation with specimens during exrusion.MnAlC powder was made by Ar gas atomizing process, classified fixed particle sizes and was compacted by extrusion at extrusion temperature: 853-993K and mean strain rate: 0.005-0.05/s.Anisotropy of MnAlC formed was found to improve at lower temperature, finer particle size and lower strain rate. It was considered to be related to the homogeneity of τ phase and the crystal grain size. It was found that anisotropy of MnAlC magnet was increased as deformation right after the start of extrusion and saturated at the part on the way of extrusion.This phenomenon can be explained by the two deformation areas, one is that dynamic recrystallization proceeds as keeping the former crystal orientation according to the strain induced grain boundary migration mechanism, the other is that dynamic recrystallization proceeds with no relation to the former crystal orientation according to the nucleation and growth mechanism.
The authors carried out drop impact tests for several soft materials under a flat frontal impact condition in which a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. The experimental results indicated that the impact force waveforms of soft materials consisted of a thorn-shaped waveform and a subsequent mountain-shaped waveform. The thorn-shaped waveform was strongly affected by the strain rate. In the present study, the occurrence mechanism of this distinctive waveform was discussed from the viewpoint of the viscosity transient phenomenon. A standard linear solid (SLS) model in which the viscosity transient phenomenon was considered was applied to the simulation. Some features of the impact force waveform of soft materials could be explained by the SLS model. Furthermore, the thorn-shape waveform could also be observed in the impact force waveforms of human skin and free-falling hollow balls.
